1. Field of the Invention
The present invention relates to a system for controlling a route bus service by first collecting information at passage points of buses running on a regular route according to a basic schedule, then estimating the time of arrival of each running bus at a terminal, subsequently modifying the basic schedule so as to enable the route buses to depart from the terminal sequentially at equal time intervals, and displaying service information such as a timetable and so forth on a service indicator installed in each bus.
2. Description of the Prior Art
In the current urban traffic where automobiles occupy a major position, there exist some serious urban problems including traffic congestion and so forth that result from overpopulated city structure, and it is of great importance to secure, in the highly dense urban road network, smooth service of transportation means such as route buses which are operated principally for the public.
Similarly in medium- and long-distance transportation means which serve for communication between cities, there may occur troubles that normal service conforming to a basic schedule fails to be achieved due to road construction or traffic accidents on regular routes.
In view of such circumstances mentioned above, one prior invention titled "Method for control of specific automobile service" is known as disclosed in Japanese Patent Publication No. 54-11878 (published on May 18, 1979).
FIGS. 1 through 3 illustrate a conventional apparatus designed for controlling the service of specific vehicles automobiles such as route buses. In FIG. 1, a central service controller 1 and ground receivers 2 . . . are connected to each other by means of circuit lines 3 . . . The ground receivers 2a, 2b, 2c are equipped with antennas 4a, 4b, 4c respectively and are installed at fixed intervals along a road 9 which is a route where buses 5 . . . run according to a basic schedule. In this example the route buses 5a, 5b, 5c are running sequentially in the order of service, and mobile radio units 7a, 7b, 7c equipped with antennas 6a, 6jb, 6c are installed in the buses 5a, 5b, 5c respectively together with service indicators 8a, 8b, 8c.
In the system having the above-mentioned constitution for controlling the operation of vehicles such as route buses, each of the service indicators 8a, 8b and 8c has such a display panel 10 as shown in FIG. 2. On the obverse side of the display panel 10, individual indication contents are exhibited with, for example, a departure indicator lamp 11 showing characters for "departure" and a standby indicator lamp 12 showing characters for "standby". Each of such indicator lamps 11, 12 internally has a blink means such as a light emitting diode. The display panel 10 is attached at an easy-to-see position for a driver in the route bus. Meanwhile, the driver ought to carry with him a service timetable 13 of FIG. 3 when leaving an office or the like to begin the daily route work. There are prepared several kinds of such timetables 13 which are different from one another depending on a schedule number column 14 and a day-of-week column 15 even for the same route. In the contents described on the timetable 13, a terminal name and stop names are shown in the uppermost row 16 . . . , and the times of passage at such bus stops are written respectively in the lower rows 17. The illustrated service timetable 13 represents an exemplary schedule No. 611 for Saturday. This timetable 13 prescribes that the bus departing from the office at 12:11 reaches a first stop "Tarumi" at 12:19, then leaves there at 12:21 after a two-minute rest to pass via a stop "Sannomiya" and reaches a turn point "Okamoto" at 12:51, subsequently leaves there at 12:56 after a five-minute rest and, via "Sannomiya" at 13:08, reaches "Tarumi" at 13:24. Ten minutes later, the bus departs from "Tarumi" at 13:34 and thereafter the service is kept according to the timetable.
The drivers on their duties with the above timetables 13 run the route buses 5a, 5b, 5c respectively according to the prescribed schedules with adjustment of the departure and arrival times of the buses in conformity to the instructions received from the service controlling system shown in FIG. 1.
Now the operation of the above service controlling system will be described below with reference to FIG. 1. First the radio waves transmitted from the running buses 5a-5c are caught by the antenna 4a-4c of the ground receivers 2a-2c installed at predetermined points on the road 9 of a service route. The waves from the buses 5a-5c are transmitted by the mobile radio units 7a-7c through the antennas 6a-6c at fixed frequencies selected with respect to the individual buses. Therefore the intervals between the route buses 5 running in the order of 5a, 5b, 5c are caught in the form of radio waves by the ground receivers 2a-2c, whose outputs are transmitted via the circuit lines 3 . . . to the central service controller 1. Then the controller 1 estimates the time required for the specific route bus to pass through the sections where the ground receivers 2a-2c are installed. Such estimation is executed by various computations based on the past data in such a manner that, for example, the time to be required for the bus 5c to pass through the section 9a between the ground receivers 2a and 2b is computed by averaging the actually required passage times of the preceding buses 5a, 5b through the section 9a. In another example, the time to be required for the route bus 5b to pass through the section 9b is estimated on the basis of the time actually required for the preceding route bus 5a to pass through the section 9b. In accordance with such estimations, service instructions are outputted from the central service controller 1 to the individual route buses 5a-5c. The instructions are exhibited by turning on the corresponding indicator lamps 11, 12 . . . in the display panels 10 of the service indicators 8a-8c. For example, when the route buses 5b, 5c pass through the ground receivers 2b, 2a, the instructions from the central service controller 1 are transmitted to the service indicators 8b, 8c via the ground receivers 2b, 2a through the antennas 6b, 6c and the mobile radio units 7b, 7c in the route buses 5b, 5c.
The central service controller 1 has a record of the mean time needed for buses to cycle the complete service route and the average speed, and calculates the expected arrival time at the ground receiver 2b coming from the ground receiver 2a using the following equation. ##EQU1##
Accordingly, the bus drivers carrying the service time tables as shown in FIG. 3 actually run the buses by receiving the service instructions on the display panel shown in FIG. 2 so that the buses are operated at a constant interval in consideration of the traffic congestion in each route section 9a, 9b and so on of the road 9.
At each bus stop, users of bus have service information displayed on a display panel 19 provided on a road unit 18, as shown in FIG. 4, to know the situation of bus service on the route and expected time needed to go to the next bus stop. The road unit 18 is associated with the ground receiver 2 shown in FIG. 1, and it is made up of a box accommodating the ground receiver 2 and the display panel 19 attached on the front of the box. The display panel 19 consists of an approach message section 19a and a service interval message section 19b. For example, the road unit at the bus stop with the ground receiver 2b has its display panel 19 indicating "BUS WILL ARRIVE SOON" in the approach message section 19a in response to the detection of passage of the bus 5c at the former ground receiver 2a and also indicating the expected time needed for the coming bus to go to the next bus stop, e.g., ground receiver 2c. The road unit also has on its display panel 19 digital indication of the lapse of time since the preceding bus 5b has passed by the ground receiver 2b in the service interval message section 19b.
The foregoing route bus service controlling system, however, has the following problems. The first problem is that in calculating the lapse of time taken by a bus for running through a unit segment such as between ground receivers 2a and 2b using the statistical average speed for the entire cycle of route, the expected lapse of time calculated as (Distance between ground receivers 2a and 2b)/(Statistical average speed in this section) is not always equal to the actual lapse of time estimated (Distance between ground receivers 2a and 2b)/(Running speed in this section) as in the occurrence of traffice congestion or traffic accident.
Namely, ##EQU2## Such a situation causes a significant difference between the service information calculated by the central service controller 1 and displayed on the route unit at each bus stop and the actual result, resulting in a degraded dependability on the displayed service information for the users and bus drivers.
In connection with the above problem, it was unclear in the determining up to what time passage data should be traced back for evaluating the statistical average speed in each route section. Because of different traffic conditions of route sections such as the degree of traffic congestion and the distance of route section, it is not possible to provide accurate service information for the bus drivers, passengers and users waiting at each bus stop through the inference based simply on the Equation (1).
Among displayed information on the display panel 19 of the road unit 18 at each bus stop, as shown in FIG. 4, information in the approach message section 19a is particularly lacking in accuracy. Namely, when a user waits for a bus at a bus stop with a road unit 18n having an associated display panel 19n and a bus is passing by the previous road unit 18n-1, the user watches the road unit 18n to read in the approach message section 19a "BUS WILL ARRIVE SOON", but the expression "SOON" is ambiguous because the wait time depends on the traffic condition between the road units 18n-1 and 18n. This means that the user does not know clearly whether the intended bus will come one minute, three minutes or five minutes later, and the user is compelled to infer the arrival time of the coming bus using information such as the lapse of time since the last bus has gone and time taken to go to the next bus stop displayed on the service interval message section 19b and the service timetable posted at the bus stop.
Moreover, the service instruction using the lamps 11 and 12 on the display panel 10 of the operation instruction unit 8 as shown in FIG. 2 does not tell the bus driver on what service diagram the bus should be run. On this account, the bus driver is required to make up an approximate service plan based on the timetable 13 shown in FIG. 3 and in consideration of a delay at that time point, which sometimes forces the driver to make a full-speed ride once the departure lamp 11 has lighted, in order to catch up with the schedule. The conventional service instruction has been not only difficult for the bus drivers, but it has compromised the matter of security in the traffic system inclusive of the passengers and other vehicles.